Adding a CRL extension to a certificate is not difficult, you just need to include a configuration file with one line. But creating a CRL file requires more steps, that’s why I needed this howto. The start of this howto is the same as my previous howto.

First we generate a 4096-bit long RSA key for our root CA and store it in file ca.key:

You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter '.', the field will be left blank.
-----
Country Name (2 letter code) [XX]:BE
State or Province Name (full name) []:Brussels
Locality Name (eg, city) [Default City]:Brussels
Organization Name (eg, company) [Default Company Ltd]:Didier Stevens
Organizational Unit Name (eg, section) []:
Common Name (eg, your name or your server's hostname) []:Didier Stevens CA
Email Address []:

The -x509 option is used for a self-signed certificate. 1826 days gives us a cert valid for 5 years.

Next step: create our subordinate CA that will be used for the actual signing. First, generate the key:

You are about to be asked to enter information that will be incorporated
into your certificate request.
What you are about to enter is what is called a Distinguished Name or a DN.
There are quite a few fields but you can leave some blank
For some fields there will be a default value,
If you enter '.', the field will be left blank.
-----
Country Name (2 letter code) [XX]:BE
State or Province Name (full name) []:Brussels
Locality Name (eg, city) [Default City]:Brussels
Organization Name (eg, company) [Default Company Ltd]:Didier Stevens
Organizational Unit Name (eg, section) []:
Common Name (eg, your name or your server's hostname) []:Didier Stevens IA
Email Address []:
Please enter the following 'extra' attributes
to be sent with your certificate request
A challenge password []:
An optional company name []:

Make sure the Common Name is different for both certs, otherwise you’ll get an error. Now, before we process the request for the subordinate CA certificate and get it signed by the root CA, we need to create a couple of files (this step is done with Linux; to create empty file certindex on Windows, you could use Notepad in stead of touch).

In my previous post about securing HTTP-connections HTTP Secure: Is Internet really broken? I was speculating about the current state of encryption security in web applications. This article is about how to actually implement a CA in detail and the req…